If the first parameter is any value other than null, it is returned unchanged. If the value in the first parameter is null, the function returns the value in the second parameter. The NVL function allows you to replace null values with a default value. SQL> SELECT * FROM null_test_tab WHERE col1 IS NULL ORDER BY id Instead they must use the IS NULL or IS NOT NULL operators. SQL> SELECT * FROM null_test_tab WHERE col1 = NULL ORDER BY id Remember, comparisons against null always result in null, so queries can't use regular comparison operators like "=" or "!=". SQL> SELECT * FROM null_test_tab ORDER BY id If we query the data in the table we see the following output. INSERT INTO null_test_tab values (4, NULL, NULL, 'THREE', 'THREE') INSERT INTO null_test_tab values (3, NULL, NULL, 'THREE', 'FOUR') INSERT INTO null_test_tab values (2, NULL, 'TWO', 'THREE', 'FOUR') INSERT INTO null_test_tab values (1, 'ONE', 'TWO', 'THREE', 'FOUR') Most of the examples in this article require the following table. For a more detailed description follow the links are the bottom of the article. This article provides a summary of the functions available for handling null values. Value.Home » Articles » Misc » Here NULL-Related Functions The NVL function to replace NULL / EMPTY / NA values with our own In these situations, the NVL function becomes very handy and we can use NULL for those employees whose COMM is NULL. Then, if we give the following command we will get the Total salary as There are some situations where NVL function becomes essential, like forĮxample, if we need to show the total salary by adding SAL+COMM columns The following command select empno,ename,job,mgr,hiredate,sal,nvl(comm,0),deptno,city from emp We can use the NVL function to replace NULL values for COMM with 0 by giving Replacement-value: The value which you want to return if the firstįor example, suppose we have table: emp, with the following structureĪs we can see the COMM column is NULL for some employees. The NVL() function has the following syntax NVL(exp, replacement-value)Įvaluate and want to replace in case it is empty Remember, a blank space is not null and also 0 is not As you must be knowing that, NULL value means undefined, empty or The NVL() function in Oracle is used to replace NULL / Empty / NA Integrity Constraints (PRIMARY KEY, NOT NULL.) DEFAULT Values Dropping Constraints Disabling and Enabling Differing Constraints Check View Info about Constraints Working with Dates Oracle Views Oracle Sequences Oracle Synonyms Indexes and Clusters Table Partitioning Altering Partition Tables Dropping Partitions Merging Partitions Splitting Partitions Coalescing Partitions Oracle Objects and Object Types Oracle TO_TIMESTAMP Number Functions (Math Functions) Character Functions Miscellaneous Functions Aggregate Functions Date and Time Functions Oracle Join Queries GROUP BY Queries, SUB Queries CUBE, ROLLUP Functions Oracle DML (INSERT, UPDATE, DELETE.) Oracle DDL (CREATE, ALTER, DROP.) COMMIT, ROLLBACK,SAVEPOINT Data Control Language (GRANT, REVOKE) Oracle SQL Tutorial Contents Introduction to Databases CODD'S Rules Datatypes and Create Table Oracle SELECT Statement Formatting in SQL*Plus UNION, INTERSECT, MINUS Operators and Sorting Query Result 60 Technical Questions 42 Backup & Recovery Questions Unix For Oracle DBA 20 Questions Oracle DBA Interview Questions Most asked Oracle DBA Interview Questions.
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